Mounting component with leads having polymeric strips

ABSTRACT

A semiconductor chip mounting component includes a support structure having top and bottom surfaces and an edge, a plurality of electrically conductive leads, not attached to a chip, each lead having a first end securement section secured to the support structure and having a connection section integral with the first end securement section projecting beyond the edge of the support structure, and a flexible polymeric reinforcement in contact with and extending along the connection section of each lead, each polymeric reinforcement being separate from the polymeric reinforcements in contact with the other leads, each polymeric reinforcement extending beyond the edge of the support structure wherein each connection section is flexible and may be individually displaced without displacement of connection sections of adjacent ones of the leads.

This is a division of application Ser. No. 08/516,290 filed on Aug. 17,1995, now U.S. Pat. No. 5,787,581 which is a divisional of applicationSer. No. 08/268,040, filed on Jun. 29, 1994, now U.S. Pat. No.5,489,749, which is a divisional of application Ser. No. 07/919,772,filed on Jul. 24, 1992, now abandoned.

The present invention relates to methods, components and apparatususeful in mounting and connecting semiconductor devices.

Semiconductor chips typically are connected to external circuitrythrough contacts on a surface of the chip. The contacts on the chiptypically are disposed in the regular patterns such as a gridsubstantially covering the front surface of the chip, commonly referredto as an “area array” or in elongated rows extending parallel to andadjacent each edge of the chip front surface. Each contact on the chipmust be connected to external circuitry, such as the circuitry of asupporting substrate or circuit panel. Various processes for makingthese interconnections use prefabricated arrays of leads or discretewires. For example, in a wirebonding process, the chip is physicallymounted on the substrate. A fine wire is fed through a bonding tool. Thetool is brought into engagement with the contact on the chip so as tobond the wire to the contact. The tool is then moved to a connectionpoint of the circuit on the substrate, so that a small piece of wire isdispensed and formed into a lead, and connected to the substrate. Thisprocess is repeated for every contact on the chip.

In the so-called tape automated bonding or “TAB” process, a dielectricsupporting tape, such as a thin foil of polyimide is provided with ahole slightly larger than the chip. An array of metallic leads isprovided on one surface of the dielectric film. These leads extendinwardly from around the hole towards the edges of the hole. Each leadhas an innermost end projecting inwardly, beyond the edge of the hole.The innermost ends of the leads are arranged side by side at spacingcorresponding to the spacings of the contacts on the chip. Thedielectric film is juxtaposed with the chip so that hole is aligned withthe chip and so that the innermost ends of the leads will extend overthe front or contact bearing surface on the chip. The innermost ends ofthe leads are then bonded to the contacts of the chip, as by ultrasonicor thermocompression bonding. The outer ends of the leads are connectedto external circuitry.

In a so-called “beam lead” process, the chip is provided with individualleads extending from contacts on the front surface of the chip outwardlybeyond the edges of the chip. The chip is positioned on a substrate withthe outermost ends of the individual leads protruding over contacts onthe substrate. The leads are then engaged with the contacts and bondedthereto so as to connect the contacts on the chip with contacts on thesubstrate.

The rapid evolution of a semiconductor art in recent years has created acontinued demand for progressively greater numbers of contacts and leadsin a given amount of space. An individual chip may require hundreds oreven thousands of contacts, all within the area of the chip frontsurface. For example, a complex semiconductor chip in current practicemay have a row of contacts spaced apart from one another atcenter-to-center distances of 0.5 mm or less and, in some cases, 0.15 mmor less. These distances are expected to decrease progressively withcontinued progress in the art of semiconductor fabrication.

With such closely-spaced contacts, the leads connected to the chipcontacts, such as the wires used in wirebonding leads in the tab processand beam leads must be extremely fine structures, typically less than0.1 mm wide. Such fine structures are susceptible to damage anddeformation. With closely spaced contacts, even minor deviation of alead from its normal position will result in misalignment of the leadsand contacts. Thus, a given lead may be out of alignment with the propercontact on the chip or substrate, or else it may be erroneously alignedwith an adjacent contact. Either condition will yield a defective chipassembly. Errors of this nature materially reduce the yield of gooddevices and introduce defects into the product stream. These problemsare particularly acute with those chips having relatively fine contactspacings and small distances between adjacent contacts.

It has been proposed to form a prefabricated lead assembly havinginwardly projecting leads with all of the inner ends of the leadsconnected to a common inner element. The common element typically is ametallic ring-like structure. In these structures, the inner end of eachlead is connected to the common element via a frangible section. Thecommon element thus restrains the inner ends of the leads againstrelative movement and hence inhibits bending or other deformation of theleads. After the leads have been bonded to the chip contact, the commonelement is broken away from the leads. A frangible section may beprovided at the juncture between the innermost end of each lead and theinner element. Systems of this nature are illustrated, for example, inThorpe, Jr. U.S. Pat. No. 4,756,080 and in Angelucci, Sr. et al, U.S.Pat. No. 4,380,042. Burns, U.S. Pat. Nos. 4,312,926 and 4,413,404 depicta generally similar arrangement in which the leads are multilayermetallic structures including a copper base with an overcoat of nickel.The frangible connection between the innermost end of each lead and theinner element consists solely of the nickel overcoat layer, therebyproviding a very thin, weak section.

In these arrangements, the common element electrically interconnects allof the leads. These interconnections must be eliminated after the leadshave been bonded to the chip. Thus, the common element must be pulledaway from the chip after the leads have been bonded to the contacts ofthe chip. All of the frangible elements must be broken eithersimultaneously or in a particular pattern as the common element ispulled away from the innermost ends of the leads. The need to remove thecommon element constitutes a significant drawback, inasmuch as this mustbe done without disturbing the delicate bonds between the lead ends andthe contacts on the chip. Perhaps for these reasons, systems utilizing acommon element have not been widely adopted.

Thus, despite the substantial time and effort devoted heretofore to theproblems associated with mounting and connecting of semiconductors,there have still been substantial, unmet needs for improvements in suchprocesses and in the equipment and components used to practice the same.

SUMMARY OF THE INVENTION

The present invention addresses these needs.

One aspect of the present invention provides a semiconductor chipmounting component. A component according to this aspect of theinvention includes a support structure having upper and lower surfacesand having a gap extending through the support structure, so that thegap extends downwardly from the upper surface to the lower surface. Thecomponent also includes at least one electrically conductive lead. Eachsuch lead has a connection section extending across the gap in thesupport structure. First and second ends of the connection section aresecured to the support structure on opposite sides of the gap. Thesecond end of each connection section is secured to the supportstructure so that the second end can be displaced downwardly relative tothe support structure responsive to a downward force applied to theconnection section. Each connection section is flexible, so that theconnection section can be bent downwardly when the second end of theconnection section is displaced downwardly relative to the supportstructure. Thus, the connection section of each lead will be supportedat both ends by the support structure during positioning of thecomponent on a semiconductor chip assembly. However, each connectionsection can be bent downwardly to engage a contact on a part of thesemi-conductor chip assembly after the component has been positioned onthe part.

Most preferably, the connection sections of the leads are connected tothe support structure so that the first end of each such connectionsection is permanently connected to the support structure, whereas thesecond end of each such connection section is detachable from thesupport structure upon application of a downward force to the connectionsection. The first end of each connection section typically isconnected, by a further portion of the lead, to a terminal mounted onthe support structure.

In a typical arrangement, the component is adapted to be positioned onthe chip itself. Thus, when the component is positioned on the chip, theconnection sections of the leads will overlie contacts on the chip. Theconnection sections are bonded to the contacts on the chip. The leadsmay have terminals remote from the connection sections for connectingthe leads, and hence the contacts of the chip, to contacts on asubstrate. In the reverse arrangement, the component according to thisaspect of the invention may be adapted for positioning on the substrate,with the connection sections of the leads overlying the substrate sothat the connection sections can be bonded to the contacts of thesubstrate. The leads may be connected to the contacts on the chipthrough terminals remote from the connection sections.

Each lead may include a second end securement section attached to thesupport structure and a frangible section connecting the second end ofthe connection section with the second end securement section, so thatthe second ends of the connection sections are attached to the supportstructure through the frangible sections of the leads. The frangiblesections can be broken upon downward displacement of the connectionsections. The frangible section of each such lead may have across-sectional area smaller than the cross-sectional area of the secondend securement section and smaller than the cross-sectional area of theconnection section.

In one preferred arrangement, each lead includes a relatively thickstructural metal layer and a relatively thin first supplemental metallayer. The connection section and the second end securement section ofeach lead incorporate the structural metal layer, whereas the frangiblesection of each lead includes the first supplemental metal layer butomits the structural metal layer. In another arrangement, the second endof each connection section may be bonded to the support structures sothat the bond may be broken upon downward displacement of the connectionsection. The first end of each such connection section may also bebonded to the support structure. Desirably, the bond between the firstend of each connection section is more resistant to breakage upondownward displacement of the connection section than the bond betweenthe second end and the support structure. For example, the bonded areaof the first end securement section may be larger than the bonded areaof the second end securement section.

In another arrangement, the frangible section of each lead may include apolymeric material. In yet another arrangement, each lead may extendonly partially across the gap in the support structure. The second endof the connection section of each lead may be disposed remote from thesupport structure. The component may incorporate a polymeric stripassociated with the connection section of each such lead and extendingco-directionally with the connection section entirely across the gap.Each such polymeric strip may be secured to the support structure onboth sides of the gap and the connection section of each lead may bebonded to the associated polymeric strip. In this case, the second endof each lead is secured to the support structure only through theassociated polymeric strip, and the lead can be displaced downwardlyrelative to the support structure with breakage or elongation of thepolymeric strip.

The support structure may incorporate a polymeric cover layer inproximity to the leads, and the polymeric strips may be formedintegrally with the polymeric layer of the support structure. Thisarrangement provides a polymeric strip overlying the connection sectionof each lead. As further discussed hereinbelow, the polymeric stripserves to reinforce the connection section of the lead. According to yeta further aspect of the invention, similar reinforcement can be appliedeven in components which do not incorporate the specific arrangement ofconnection sections supported at both ends by the support structure asdiscussed above. According to this aspect of the invention, a mountingcomponent may include a flexible, continuous polymeric reinforcement incontact with each lead at an edge of the support structure so that thepolymeric reinforcement will inhabit stress concentration in the lead atsuch edge when the lead is bent downwardly to engage a contact. Mostpreferably, the polymeric reinforcement associated with each leadincludes a polymeric strip overlying the connection section of the lead.Desirably, the polymeric strips associated with the various leads areintegral with a polymeric layer of the support structure.

Most preferably, the support structure is formed from dielectricmaterials such as polymeric materials, so that the support structuredoes not electrically interconnect the leads with one another. Thesupport structure may have appreciable thickness, i.e., an appreciabledistance between its upper and lower surfaces. The leads may be disposedat an appreciable distance above the lower surface of the supportstructure. Thus, each connection section is supported above the frontsurface of the chip or substrate by the support structure before suchconnection section is displaced downwardly to engage a contact. Forexample, the support structure may include a plurality of layers with atop layer defining the upper surface of the structure and a bottom layerdefining the lower surface. The leads may be disposed above the bottomlayer. The component may include terminals disposed on the supportstructure. In a particularly preferred arrangement, the terminals, aswell as the leads are disposed above the bottom layer and the bottomlayer is resilient so as to permit downward displacement of theterminals.

The gap in the support structure may be formed as an elongated slot. Theconnection sections of many leads may extend across such slot. Theconnection sections extending across each such slot are disposed inside-by-side, substantially parallel arrangement. Some of the leadsassociated with each such slot may have their first ends disposed at afirst edge of the slot and a second edge of the slot, whereas theremaining leads associated with the same slot may have the reversearrangement, i.e., the first end of the lead disposed at the second edgeof the slot and the second end of the lead connection section disposedat the first edge of the slot. This arrangement is particularly usefulwhere some of the leads associated with each slot are connected to theterminals disposed on one side of the slot, whereas others are connectedto terminals disposed on the opposite side of the slot. Such anarrangement can be used, for example, with semiconductor chips havingelongated rows of contacts.

Alternatively, the gaps in the support structure may be relatively smallholes extending through the support structure. One lead, or a few leads,may extend across each such hole. There may be numerous holes disposedat various locations on the support structure. For example, the holes,and the leads, may be disposed in an array substantially covering thetop and bottom surfaces of the support structure as, for example, wherethe component is to be used with a chip or other element having contactsin a “area array” on substantially the entirety of its front surface.

A further aspect of the invention provides methods of making connectionsto contacts on a part of a semiconductor chip assembly, such as tocontacts on a front surface of a semiconductor chip or contacts on achip mounting substrate. Methods according to this aspect of theinvention desirably include the steps of juxtaposing a connectioncomponent, such as a component described above, with the part so that abottom surface of the support structure in the component facesdownwardly, towards the surface of the part and the top surface of theconnection component faces upwardly, away from the front surface of thepart. The connection component is juxtaposed with the part so that eachcontact on the part surface is aligned with a gap in the supportstructure and so that connection sections of leads extending across thegap are disposed above the contacts. The support structure supports eachconnection section at both sides of each such gap during the juxtaposingstep, so that the connection section does not tend to bend or deform atthis stage of the process.

The method desirably further includes the step of bonding eachconnection section to a contact on the part by displacing eachconnection section downwardly so as to displace one end of each suchconnection section downwardly relative to the support structure andbring the connection section into engagement with the contact of thepart. Preferably, the bonding step is performed so as to detach one endof each connection section from the support structure during thedownward displacement of the connection section as, for example, bybreaking a frangible portion of each lead or detaching a bond betweenthe lead and the support structure as discussed above. The bonding stepmost preferably includes the step of engaging each connection sectionwith a recess in a bonding tool so that the bonding tool at leastpartially controls the position of the connection section in lateraldirections transverse to the downward travel of the bonding tool.

The use of the bonding tool to guide and constrain the lead during thebonding step may be applied even where the connection component does nothave the connection sections connected to the support structure at bothends. Thus, the step of guiding the connection section of the lead withthe bonding tool may be employed even where the leads are cantileveredfrom an edge of the support structure. Most preferably, the methodsaccording to this aspect of the invention further include the step ofaligning the bonding tool with the contacts on the part, such as withcontacts of a semiconductor chip. Preferably, the step of engaging thebonding tool with the leads is performed so that the bonding toolactually brings the leads into alignment with the contacts. That is, thecontact sections of the leads may be slightly out of alignment with thecontacts, but the bonding tool moves the leads in directions transverseto the leads as the bonding tool is engaged with the leads, therebybringing each lead into alignment with the contacts. Thus, it isunnecessary to achieve exact alignment between the connection sectionsof the leads and the contacts on the part when the connection componentis first applied to the part. Any slight misalignment will be correctedby action of the bonding tool.

Typically, each connection section is an elongated, strip-like structureand the bonding tool has an elongated groove in its bottom surface. Thebonding tool is positioned above each contact so that the groove extendsin a pre-selected groove direction and extends across the top of acontact. The connection sections of the leads extend generally parallelto the groove direction, so that when the bonding tool is advanceddownwardly to engage the lead, the connection section of each lead isseated in the groove. If the lead is slightly out of alignment with thegroove, the lead will be moved in lateral directions, transverse to thegroove, until it seats in the groove and thus becomes aligned with thecontact.

Yet another aspect of the present invention provides a tool for bondingleads to contacts on a semiconductor chip, substrate or other part of asemiconductor chip assembly. A tool according to this aspect of theinvention desirably includes a generally blade-like body defining abottom edge and a groove extending lengthwise along such bottom edge forengaging leads to be bonded. The tool desirably also includes means forconnecting the tool to a bonding apparatus so that the bottom edge ofthe tool faces downwardly. Such a blade-like tool can be used in methodsas aforesaid. Most preferably, the groove has a central plane andsurfaces sloping upwardly from the sides of the groove towards thecentral plane. These sloping surfaces will tend to guide a lead engagedwith the tool towards the central plane of the groove.

Yet another aspect of the invention provides methods of makingsemiconductor components. Methods according to this aspect of theinvention include the steps of providing one or more conductive leads,each lead having an elongated connection section. The method furtherincludes the step of forming a dielectric supporting structureincorporating one or more gaps aligned with the connection sections ofthe leads so that each lead is permanently secured to the supportingstructure of one end of the connection section and releasably secured tothe supporting structure of the other end of the connection section. Theleads may be provided on a sheet-like dielectric support layer and maybe supported by such layer. The step of forming the support structuremay include the step of selectively removing a part of the dielectriclayer to form a gap therein in alignment with the connection sections ofthe leads.

The step of providing the leads may include the step of forming eachlead with a fragile section in the connection section. For example, theleads may be formed by providing strips of a conductive structuralmaterial so that each such strip has an interruption therein, anddepositing a first supplemental material so that such supplementalmaterial overlies each strip at least in a zone of the strip includingthe interruption, so as to leave portions of the strip on opposite sidesof the interruption connected to one another by the first supplementalmaterial. Thus, the frangible section of each lead may include a sectionformed from the supplemental material. The structural material and thesupplemental material may both be metals and the supplemental materialmay be applied an a thin layer in a plating process. The dielectriclayer may be formed from a polymeric material such as polyimide and thestep of selectively removing a portion of the dielectric layer may beperformed after forming the strips. That is, the strips are deposited onthe dielectric sheet and the dielectric sheet is then etched orotherwise selectively treated so as to form the gap or gaps. Afterformation of the gap or gaps, one end of each connection section remainsconnected to the dielectric layer only through the frangible section,and hence is releasably connected to the dielectric sheet.

Alternatively, the leads may be formed by depositing strips of aconductive material on the dielectric sheet and then etching thedielectric sheet to form the gap or gaps. The dimensions of the gap orgaps so formed are controlled so as to leave each lead with a relativelylarge first end securement section bonded to the dielectric sheet on oneside of the gap and with a relatively small, second end securementsection bonded to the sheet on the other side of the gap, so that theend of each lead adjacent such other section can be detached from thedielectric sheet by breaking this relatively small bond. In thisinstance, there is no need to form a frangible section in each lead.

The foregoing and other objects, features and advantages of the presentinvention will be more readily apparent from the detailed description ofthe preferred embodiments set forth below, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic plan view of a semiconductor connectioncomponent in accordance with one embodiment of the invention.

FIG. 2 is a fragmentary, diagrammatic, partially sectional viewdepicting a portion of the component illustrated in FIG. 1.

FIG. 3 is a diagrammatic, fragmentary, sectional view on an enlargedscale taken along line 3—3 in FIG. 2.

FIG. 4 is a diagrammatic plan view of a chip and another element usedwith the component of FIGS. 1-3.

FIG. 5 is a view similar to FIG. 2 but depicting the component of FIG. 2in conjunction with the components of FIG. 4 during an assembly process.

FIG. 6 is a diagrammatic side elevational view of a tool utilized in theassembly process of FIG. 5.

FIG. 7 is a diagrammatic end elevational view of the tool depicted inFIG. 6.

FIG. 8 is a fragmentary, sectional view on an enlarged scale depictingportions of the tool of FIG. 6 and the components of FIGS. 1-5 duringthe assembly process.

FIG. 9 is a view similar to FIG. 2 but depicting portions of a componentin accordance with a further embodiment of the invention.

FIG. 10 is a fragmentary, sectional view depicting portions of acomponent in accordance with yet another embodiment of the invention.

FIG. 11 is a fragmentary, sectional view depicting the component of FIG.10 in conjunction with a semiconductor chip after an assembly process.

FIG. 12 is a fragmentary, plan view depicting the component of FIG. 10.

FIGS. 13 and 14 are fragmentary, sectional views similar to FIGS. 10 and11 respectively but depicting a component in accordance with yet anotherembodiment of the invention.

FIG. 15 is a view similar to FIG. 2 but depicting a component inaccordance with a further embodiment of the invention.

FIG. 16 is a fragmentary, partially sectional perspective view depictingthe component of FIG. 15 and a chip after an assembly process.

FIGS. 17, 18 and 19 are fragmentary, diagrammatic sectional viewsdepicting additional components in accordance with further embodimentsof the invention.

FIGS. 20A through 20G are diagrammatic sectional views depicting afabrication process in accordance with an embodiment of the invention.

FIGS. 21A through 21H are diagrammatic sectional views similar to FIGS.20A through 20G but depicting another fabrication process in accordancewith another embodiment of the invention.

FIG. 22 is a diagrammatic perspective view illustrating an assemblyincorporating a component according to yet another embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A semiconductor connection component in accordance with one embodimentof the invention has a supporting structure 30 incorporating a flexibletop dielectric layer 32 and a bottom, compliant dielectric layer 34(FIG. 2). Body 30 is generally sheet-like and has a top surface 36defined by top layer 32 and a bottom surface 38 defined by bottom layer34. The terms “top” and “bottom” are used herein to indicate directionsrelative to the structure of the connection component itself. It shouldbe understood as referring to the frame of reference of the componentitself, and not to the ordinary, gravitational frame of reference.Likewise, the terms “upwardly” and “downwardly” should also beunderstood as referring to the frame of reference of the componentitself. Top layer 30 may be about 0.01 to about 0.1 mm thick, whereasbottom layer 34 may be about 0.05 to about 1.0 mm thick. Supportstructure 30 may be formed as part of a large, substantially continuousstrip-like tape 33 containing a plurality of such support structures.

Support structure 30 has four gaps 40 in the form of elongated slotsextending through the support structure, from the top surface 36 to thebottom surface 38. The gaps or slots 40 subdivide structure 30 into aninterior portion 42 substantially bounded by the gaps 40 and fourstrip-like outer securement elements 44 disposed outside of the gaps,the securement elements 44 being connected to the central portion 42 bybridge elements 46. As best seen in FIG. 1, the gaps or slots 40 definea generally rectangular pattern, with the slots defining the edges ofthe rectangle and the bridge elements 46 being disposed at the cornersof the rectangle.

The component also includes a plurality of central terminals 48 disposedon the central region 42 of the support structure and a plurality ofoutside terminals 50 disposed on the securement elements 44. For clarityof illustration, the drawings depict only a relatively small number ofcentral terminals 48 and outside terminals 50. In actual practice,however, there may be hundreds or even thousands of terminals. Eachcentral terminal 48 is associated with a central terminal lead 52,whereas each outside terminal 50 is associated with an outside terminallead 54. As best seen in FIG. 2, each central terminal 48 is disposedbetween top layer 32 and bottom layer 34 on the central region 42 of thesupport structure. Each of the terminals 48 is exposed at the topsurface of the component, through apertures in the top dielectric layer.The central terminal lead 52 associated with each such central terminal48 is formed integrally with that central terminal and extends from ittowards the periphery of the support structure, outwardly across one ofthe slots 40. Each central terminal lead thus includes an elongatedconnection section 56 extending across the associated gap or slot 40. Afirst end 58 of each such connection 56 lies at the first side 60 of theslot 40, at the central region 42, whereas the second end 62 of eachsuch connection section 56 lies adjacent the second, opposite side 64 ofthe slot, adjacent the securement element 44. Each central terminal lead52 also includes a first end securement section 66 extending from theassociated terminal 48 to the first end of the connection section. Thefirst end securement section and the connection section of each suchlead merge with one another at first edge 60 of gap 40. Each centralterminal lead also includes a second end securement section 70 attachedto the securement structure 44 on the second side of slot 40. Eachcentral terminal lead 52 also includes a frangible section 72 disposedbetween the second end 62 of the connection section 56 and second endsecurement section 70.

As best seen in FIG. 3, each central terminal lead includes a structuralmetal layer 74, a first supplemental metal layer 76 above the structuralmetal layer 74 and a second supplemental metal layer 78 below thestructural metal layer 74. All of these layers are present throughoutthe entirety of each central terminal lead 52, except that the secondsupplemental layer 78 and the structural metal layer 74 are interruptedat the frangible section 72. Stated another way, the frangible section72 consists only of the first supplemental layer 76. Thus, theconnection section 56 includes all three metal layers 74, 76 and 78, asdoes the second end securement section 70, whereas the interveningfrangible section 72 includes only the first supplemental layer 76. Thesupplemental metal layers are substantially thinner than the structuralmetal layer 56. The frangible section has a groove or notch 80 extendingacross the lead. As best appreciated with reference to FIG. 2, thegroove or notch 80 of each such frangible section 72 is transverse tothe direction of elongation E of the connection section 56. Because eachsuch frangible section 72 consists only the first supplemental metallayer 76, the cross-sectional area of the lead in the frangible section72 is substantially less than the cross-sectional area of the connectionsection 56 and less than the cross-sectional area of the second endsecurement section 70. As used in this disclosure, references to the“cross-sectional” areas of the leads should be understood as referringto the cross-sectional area in an imaginary cutting plane, such ascutting plane 82, transverse to the elongation direction of the lead,i.e. the cross-sectional area of the lead portion in question seen whenviewing in the elongation direction E (FIG. 2).

Structural metal layer 74 (FIG. 3) desirably is about 0.01 mm to about0.05 mm thick, whereas each of the supplemental metal layers 76 and 78desirably is about 1 micron to about 75 microns thick. In each case, thethickness is measured in the vertical direction. The width W of theconnection section 56 in the horizontal direction transverse to thethickness of the lead and transverse to the direction of elongation E ofthe connection section desirably is between 0.025 and about 0.25 mm. Thefrangible section 72 has substantially the same width but a very smallthickness, equal only to the thickness of the first supplemental layer76.

Typically, the supplemental metal layers are applied as platings orcoatings on the structural metal layer 56. Structural metal layer 74preferably is formed from a metal selected from the group consisting ofcopper, platinum, gold, nickel, aluminum, silver, alloys of these metalswith other metals and combinations of such metals and alloys. Of these,silver generally is less preferred whereas gold is more preferred. Thesupplemental metal layers may be formed from metals selected from thesame group. Gold, nickel and copper are particularly preferred assupplemental metal layers. Typically, the supplemental metal layers areformed from a different metal than the structural metal layer.

The outside terminal leads 54 are identical to the central terminalleads 52 except that the positions of the various elements in theoutside terminal leads are reversed. Thus, each outside terminal lead 54has a connection section 86 extending across one of the slots 40. Thefirst end 88 of each such connection section 86 is disposed adjacent thesecond edge 64 of slot 40, i.e., adjacent the securement element 44,whereas the second end 90 of each such connection section is disposedadjacent the first edge 60 of the slot and hence adjacent the centralregion 42 of the securement structure. The first end securement section92 of each outside lead 54 is mounted to the securement element 44,whereas the second end securement section 94 of each such lead ismounted to the central region 42 of the support structure. Each outsideterminal lead is provided with a frangible section 96 disposed betweenits second end securement section 94 and the second end 90 of itsconnection section 86. The widths and thicknesses of the variouselements in each outside lead are identical to those of the centralterminal leads discussed above.

The connection sections 56 and 86 of the various leads extend acrosseach slot 40 in a generally side-by-side array. Thus, the elongatedconnecting portions of the various leads associated with each gap orslot 40 extends substantially parallel to one another. The elongationdirections of all of these connecting portions associated with each slotare substantially transverse to the direction of elongation of the slotitself. The spacings between adjacent connection sections are selectedso that the center-to-center distances between connection sections areequal to the center-to-center distances between contacts on the chip tobe connected. Thus, the center-to-center distances between adjacentconnection sections 56 and 86 in a given slot 40, measured in thelengthwise direction of the slot, transversely to the directions ofelongation of the connection sections may be about 0.5 mm or less andmay preferably be about 0.25 mm or less. Also, the dimensions of supportstructure 30, including the distances between slots 40 are likewiseselected to match the distances between contact rows on the chip.

The connection component discussed above with reference to FIGS. 1-3 maybe utilized in conjunction with a semiconductor chip 98 seen in FIG. 4.Chip 98 may be a conventional semiconductor chip generally in the formof a rectangular solid having a generally planar front surface 99 withfour rows 100 of electrical contacts 102 disposed on such front surfaceadjacent the edges thereof. The contacts in each such row are disposedalong the longitudinal axis 140 of the row. As further discussed below,a generally rectangular collar or supporting ring 104, having agenerally planar front or top surface 106 may be employed in conjunctionwith chip 98. Ring 104 is dimensioned so as to closely surround chip 98.Also, ring 104 has the same thickness as chip 98, so that the topsurface 106 of the ring will lie substantially flush with the frontsurface 99 of the chip when the ring and the chip are disposed on a flatsupporting structure.

In one assembly process according to an embodiment of the invention,chip 98 and ring 104 are disposed on a flat surface (not shown) in theorientation illustrated in FIG. 4. The connection component is disposedatop the chip and ring as shown in FIG. 5, with the bottom surface 38 ofthe connection component support structure facing downwardly andabutting the top surfaces 99 and 106 of the chip and ring and with thetop surface 36 of the connection component support structure facingupwardly, away from the chip. The slots or gaps 40 in the connectioncomponent support structure are substantially aligned with the rows ofcontacts 102 on the chip, one such aligned slot 40 and contact row 100being illustrated in FIG. 5. Thus, the lengthwise direction of each slotextends generally parallel to the lengthwise axis 140 of the aligned rowof contacts, whereas each of the connection sections 56 and 86 extendingacross such slot extend transverse to such lengthwise axis.

The connection component may be placed on the chip using conventionalautomatic pattern recognition systems and automatic positioning elementsto assure the desired placement of the connection component relative tothe chip. Thus, the pattern recognition equipment is linked to afeedback system for controlling either the position of the chip or theposition of the connection component so as to align the slots or gaps 40with the rows of contacts on the chip, and to bring the connectionsections of the individual leads into alignment with the correctcontacts 102 themselves. Automatic positioning equipment and methods perse are well-known and hence need not be described further herein.Despite such automatic positioning equipment and methods however, therewill still be some misalignment between the connection sections and thecontacts. For example, tolerances on the size and shape of theconnection component may result in some individual leads being slightlymisaligned with the associated contacts on the chip even when otherleads are perfectly aligned. It is difficult to achieve perfectalignment of the connection sections of all the leads and all of thecontacts on the chip by adjusting the relative positions of the entireconnection component and chip. Preferably, however, any misalignment ofan individual lead connection section and the associated contact in thelateral or width-wise directions of the connection section amounts toless than about one-half the center-to-center distance between adjacentconnection sections, i.e., less than about one-half of the spacingbetween adjacent contacts on the chip. Thus, the connection sections ofthe individual leads at this stage of the process are crudely alignedwith the contacts in the lateral directions. Positioning of theconnection sections relative to the contacts on the chip in theelongation directions is considerably less critical. Because theconnection sections are elongated, each elongation section may bedisplaced from its nominal position relative to the associated contacton the chip by a considerable amount, up to about one-half the length ofthe connection section, while still leaving a portion of the connectionsection in an appropriate position for engagement with the chip contactin subsequent stages of the process.

In the next stage of the process, a bonding tool 110 is employed. Asbest seen in FIGS. 6, 7 and 8, bonding tool 110 has a generally flat,blade-like body 112 with a pair of opposed side surfaces 114 (FIG. 7) apair of vertical edges 116 (FIG. 6) and a lower edge 118 extendingbetween vertical edges 116. The tool has an elongated first groove 120 aformed in lower edge 118 and extending inwardly along such lower edgefrom one vertical edges 116 a to a coupling portion 130 adjacent themidpoint of lower edge 118. Groove 120 occupies substantially the entirewidth of lower edge 118. As best seen in FIG. 8, groove 120 has opposedsides 122 adjacent the opposite faces 114 of body 112, and has surfaces124 sloping upwardly from sides 122 to the central plane 126 of thegroove, midway between sides 122. Groove 120 merges with a verticalgroove 128 a extending upwardly along the adjacent edge 116 a of thebody. Groove 128 tapers in depth so that the depth of this groovegradually decreases towards the upper end thereof. The tool has a radiusat the corner between lower edge 118 and vertical edge 116 a. Thegrooves 120 a and 128 a extend around these radii and merge with oneanother at such radii.

The tool also has a generally flat coupling portion 130 extendingtransversely across lower edge 118, from one of the faces 114 to theother, midway between vertical edges 116. Coupling portion 130 defines abottom surface 131 (FIG. 8) approximately flush with the edges 122 ofgroove 120 a. The bottom surface 131 has small ridges, grooves or otherroughening features (not shown). The bottom edge of the tool is alsoprovided with a second groove 120 b extending lengthwise along thebottom edge 118 from coupling portion 130 to vertical edge 116 b,opposite from edge 116 a. Groove 120 b and edge 116 b are similar togroove 120 a and edge 116 a discussed above. Thus, a vertical groove 128b on edge 116 b joins groove 120 b. Tool 110 also has a shank 132extending upwardly from the top of blade-like body 112, the shank havinga screw tip 134 and shoulder 136 at its upper end, remote from body 112.These features are adapted to mate with the tool holder 138 of a bondingapparatus so that the tool may be held in an operative position on theapparatus and so that force and energy from the apparatus may bedirected downwardly through the tool as discussed below. The screw tip134 and shoulder 136 are merely illustrative. The exact configuration ofthe features which hold the tool to the apparatus will vary with thenature of the apparatus employed. Any such features and/or shapes whichwill allow the tool to meet with the particular bonding apparatus can beemployed. Further illustrations of such features include bolt holes inthe tool for mating with bolts on the apparatus, bayonet locks, taperlocks and/or straight shanks for engagement in a chock or collet.

In the bonding step of the assembly process, the assemblage of the chip98, ring 104 and the connection component is aligned with the body 112of tool 110 so that the elongated groove 120 is aligned with a contact102 on the chip. Such alignment can be achieved by moving the chip andother associated components relative to the bonding apparatus undercontrol of an automatic vision system or other system for monitoring theposition of the chip. The tool is oriented so that groove 120 extendssubstantially transverse to the direction of the row of contacts, i.e.,substantially transverse to the lengthwise axis 140 of the contact row(FIG. 5). The groove 120 thus is roughly aligned with the elongationdirections E of the connection sections 56 and 86 of the connectioncomponent leads overlying that particular row of contacts. However, itshould be understood that, in this embodiment, the alignment isestablished between the tool and the chip, and not between the tool andany element of the connection component. Thus, to the extent that theconnection section of a particular lead is out of alignment with theassociated contact on the chip, in a lateral direction transverse to thedirection of elongation of such lead, such lead connection section willbe out of alignment with the tool as well. Provided that the connectionsections of the leads have been crudely aligned with the contacts asdiscussed above, however, any minor remaining misalignment will becorrected by the tool itself during the next step.

Once the tool and the contact of the chip are in alignment, the tool isadvanced downwardly, in the direction indicated by arrow 142 in FIG. 5,so as to force the connection section of the most closely aligned leaddownwardly. As best appreciated with reference to FIG. 8, as theinwardly sloping surfaces 124 of grooves 120 a and 120 b engage theconnection section 56 of a lead, they displace the lead laterally,towards the central plane 126 of the groove and hence into preciselateral alignment with the contact 102. As the tool moves downwardlyunder the influence of forces applied by the bonding apparatus, itdisplaces the connection section 56 downwardly relative to the supportstructure 30 of the connection component. As the second end 62 of theconnection section 56 is forced downwardly, frangible section 72 breaks,thereby freeing the second end from the securement element and detachingthe same from the support structure. The first end 58 of each suchconnection section bends downwardly so that the freed connection sectioncan be forced into engagement with the aligned contact 102 by the tool.At the time the second end 62 of each connection section 56 is detachedfrom the support structure, it is already engaged with the groove 120 ofthe tool. At this time, the support provided to the second end of theconnection section to prevent lateral displacement is no longernecessary or desirable. As the tool forces the connection section intoengagement with the contact 102, heat and/or ultrasonic vibrations maybe applied by the bonding apparatus through the tool so as to cause theconnection section to bond to the contact. The lower surface 131 ofcoupling section 130 bears on the connection section of each lead toforce it against the contact. Applied vibrations may be directed alongthe lengthwise dimension of groove 120, and hence generally along thedirection of elongation of the connection section. The roughened surfaceof coupling section 130 aids in coupling the tool to the connectionsections of the lead for transmission of vibrations therebetween. In afurther embodiment, the coupling section 130 may be arranged to protrudedownwardly beyond the adjacent sections of the tool lower edge 118.

After the connection section of one lead has been bonded to a contact,the tool is retracted upwardly and advanced along the direction of theaxis 140 of the contact row. The tool is then aligned with the nextcontact, and the process is repeated. On some repetitions of the bondingoperation, the tool will engage the connection sections 86 of theoutside terminal leads 84. The tool is operated in the same manner tobond the outside terminal leads. However, the frangible section whichbreaks is oh the opposite side of the slot 40.

Once this bonding process has been performed for all of the leads, thecontacts 102 are connected to the central terminals 48 and outsideterminals 50 of the securement element. The subassembly is then readyfor testing and further use. As discussed in greater detail inco-pending, commonly assigned U.S. patent application Ser. Nos.07/586,758, filed Sep. 24, 1990 and 07/673,020 filed Mar. 21, 1991, andin published International Application W092/05582, (Application No.PCT/US91/06920), the disclosures of which are hereby incorporated byreference herein, the compliant bottom dielectric layer 34 permitsdisplacement of the terminals 48 and 50 in the vertical directiontowards the front surface 99 of the chip and towards the top surface 106of the ring. This facilitates engagement of a multiplicity of theterminals with a multiplicity of test probes simultaneously. Compliantlayer 34 may have the structure shown in said earlier applications. Asmore fully described therein, the compliant layer may incorporate holesand masses of compliant material, the masses being aligned with theterminals. As described in said co-pending applications, subassembliesincorporating a connection component (also referred to as a“interposer”) may be mounted to a substrate such as a circuit panel orsemiconductor package. The terminals 48 and 50 of the connectioncomponent are connected to contact pads on the substrate. As describedin detail in said co-pending applications, the terminals 48 and 50 onthe connection component can move relative to the contacts 102 of thechip, typically in directions parallel to the front surface 99 of thechip. This provides compensation for differential expansion andcontraction of the chip and substrate.

The connection component shown in FIG. 9 is similar to the componentdescribed above. It incorporates a support structure 230 having aflexible top layer 232 and a compliant dielectric bottom layer 234.However, the gaps 240 in the support structure are not formed aselongated slots, but, instead, are formed as individual holes. Theseholes 240 are substantially equally distributed over the entire surfacearea of the support structure 240. Each lead 252 is associated with onesuch hole, and each lead has a connection section 256 extending acrosssuch hole. Each such connection section has a first end 258 adjacent oneside of the hole, and a second end 262 adjacent the other side of thehole. Once again, the first end 258 of the connection section isconnected by a first end securement section 266 to a terminal 248,whereas the second end 262 of the connection section is connected to athin, frangible section 272, which, in turn, is connected to a secondend securement section 270 attached to the support structure. Thus, thesecond end 262 of the connection section is attached to the supportstructure through the frangible section 272. The terminals 248 on thestructure of FIG. 9 protrude above the top layer 232. Essentially anyterminal configuration can be employed, provided that the terminals arein electrical contact with the leads.

Components according to this embodiment of the invention can be used inessentially the same way as the components discussed above. Thesecomponents are employed with chips having contacts disposed in a “areaarray” of contacts distributed over substantially the entire area of thechip front surface. The connection component is disposed on the chipfront surface so that each contact on the chip is aligned with one holeand crudely aligned with the connection section 256 of one lead. Abonding tool as discussed above is advanced into each hole so as toengage the connection section of the associated lead. Once again, thebonding tool is aligned with the contacts on the chip. Engagement of thebonding tool with the connection section serves to bring the connectionsection into precise alignment with the contact.

A connection component according to a further embodiment of theinvention is illustrated in FIG. 10. That component 302 has a supportstructure incorporating only a single dielectric layer 332 having one ormore gaps 340 therein. A lead 352 extends along the underside of layer322. Lead 352 incorporates a connection section 356 extending across gap340. A first end securement section 366 of lead 352 is electricallyconnected to a terminal 348 and is permanently bonded to layer 322.First end securement section 366 is disposed adjacent the first end ofconnection section 356. The second end 362 of connection section 356 isconnected to a second end securement section 370 which, in turn, isreleasably bonded to the underside of layer 322. Thus, the bond betweenfirst end securement section 366 and layer 322 is considerably strongerthan the bond between second end securement section 370 and layer 322.Such differences in bond strength may be achieved in several ways. Asillustrated in FIG. 12, at least that portion of first end securementsection 366 adjacent gap 340 may have a width W greater than the width Wof the second end securement section 370.

The connection components 302 of FIG. 10 is employed in conjunction witha separate underlayer 304. Underlayer 304 consists essentially of alayer of dielectric material having gaps 306. The gaps 306 in underlayer304 are arranged in a pattern corresponding to the pattern of gaps 340in the dielectric layer of the support structure in the connectioncomponent itself. In use, the underlayer 304 is applied on the frontsurface of the chip, and connection component 302 is applied on top ofthe layer 304. Thus, as seen in FIG. 11, when used with the separatebottom layer 304, the connection component 302, and hence the connectionsections 356 of the leads are supported above the front surface of chip308. Once again, while the component is being positioned, the connectionsections 356 are supported at both sides of the gaps 340. In the bondingprocess, a bonding tool as discussed above is employed to force eachconnection section downwardly, into engagement with the contact 310 ofthe chip. In this operation, the second end securement section 370 isdetached from the dielectric support structure layer 322 of component302, whereas the first end securement section 366 and hence the firstend of connection section 356 remains attached to such layer. Statedanother way, the second end of each connection section 356 is releasedfrom its attachment with the support structure through peeling orbreakage of the bond between the second end securement section and thesupport structure, rather than by breakage of a frangible section in thelead itself. In this arrangement, the lead does not incorporate afrangible section and hence there is no need for the supplemental layersdiscussed above with reference to FIG. 3. Desirably, the connectionsection of the lead consists essentially of a metal selected from thegroup consisting of copper, gold, nickel, silver, aluminum, platinum andcombinations thereof, gold and gold alloys being particularly preferred.Essentially pure gold is especially preferred

The component 402 illustrated in FIGS. 13 and 14 is generally similar tothe component 302 described with reference to FIGS. 10-12. However, thesupport structure includes both a top layer 422 and a bottom layer 434permanently connected together. Here again, a connection section of thelead extends across the gap 440 in the top layer of the supportstructure. The second end of section 456 is connected to a second endsecurement section 470, which section is releasably bonded to the toplayer 422 of the support structure. However, the end of section 470remote from connection section 456 is, in turn, attached to a furthersection 472 of the lead. That further section is permanently mounted tothe support structure. As seen in FIG. 14, when connection section 456is displaced downwardly, the second end 462 of the connection section,adjacent one side of the gap, is also displaced downwardly. The secondend securement section 470 peels away from the top layer 422 to permitsuch downward displacement of the second end. In this embodiment,however, the second end 462 of the connection section remains looselyattached to the support structure through the second end securementsection and the further section 472. This arrangement is generally lesspreferred than the other arrangements discussed above because the leadwill be stretched somewhat during the assembly process, in deformingfrom the configuration of FIG. 13 to the configuration of FIG. 14. Forthis embodiment, it is particularly desirable to form the leads fromgold, inasmuch as gold has excellent ductility to accommodate thestretching encountered in the assembly process.

The component 502 illustrated in FIGS. 15 and 16 has a bottom layer 534and a top layer 532 similar to those discussed above, the top layer 532being formed from a polymeric dielectric material, such as polyimide.Here, again, each lead includes a structural metal layer 574, a firstsupplemental layer 576 overlying the top surface of the structural metallayer 574 and a second supplemental metal layer 578 on the bottomsurface of layer 574. This layered metallic structure extends throughouta first end securement section 566 overlying the supporting structure,and also throughout connection section 556 and second end securementsection 570. Each lead further includes a polymeric strip 510 formedintegrally with the top layer 532 of the support structure. The topsurface of the metallic lead structure, i.e., the top surface of thefirst supplemental metal layer 576 and the underlying top surface ofstructural layer 574 are generally flat. Each polymeric strip 510closely overlies the top surface of one such metallic structure and isbonded thereto, so that each such polymeric strip becomes, in effect,part of the underlying lead. As in the component discussed above withreference to FIGS. 1-3, the second end 562 of each connection section556 is attached to the second end securement section 570 of the leadthrough a frangible section 572. Within each frangible section, themetallic structure is entirely omitted, so that the frangible sectionconsists only of the polymeric strip 510. In a variant of this approach,the topmost or first supplemental layer 576 may be continued through thefrangible section, so that the frangible section incorporates bothpolymeric strip and the relatively thin supplemental metal layer. In afurther variant, one or both of the supplemental metal layers may beomitted. The structural metal layer 574 may be entirely omitted in thefrangible section 572, or may be formed with a substantially reducedthickness and/or width in such section. The component of FIG. 15, likethe component of FIGS. 1-3, has leads extending from both sides of thegap 540. Thus, some of the frangible sections 572 are disposed adjacentone side of the gap, whereas others are disposed adjacent the other sideof the gap.

The component of FIG. 15 is assembled to a semiconductor chip 590 andring 592 in substantially the same way as the component of FIGS. 1-3. Asthe connection sections 556 of the various leads are forced downwardlyinto engagement with the contacts 594 of the chip, the portions of thepolymeric strips constituting the frangible sections 572 of the leadsbreak, thereby detaching the second ends 562 of the connection sections556 from the support structure. In the structure remaining after theleads have been bonded to the contacts (FIG. 16), each lead has asecurement section 566 secured to a part of the support structure 530and the connection section of each lead projects beyond an edge of thesupport structure. For example, the connection section 556 a of one leadprojects beyond an edge 541 of the securement structure 530 at one sideof gap 540. The securement section 556 b of another lead projects intogap 540 from the other side, and hence projects beyond edge 543 on theopposite side of the gap. The projecting connection section of each suchlead is flexed downwardly at and adjacent to the associated edge. Forexample, the connection section 556 a is flexed downwardly at edge 541.The polymeric strips 510 and the polymeric top layer 532 of the supportstructure, formed integrally therewith, serve to reinforce thedownwardly flexed portions of the leads. In particular, the polymericstrips and polymeric top layer reinforce the metallic structures of thelead and protect it from stress concentrations.

The embodiment illustrated in FIG. 17 is similar to that described abovewith reference to FIGS. 15 and 16. Here, again, polymeric strips 610integral with the top layer 632 of the support structure extend acrossthe gap 640. However, the leads do not have discrete second endsecurement sections. Rather, the metallic structure in the connectionsection 656 of each lead terminates at the second end 662 of suchconnection section remote from the edge 643 of gap 640. Each such secondend is secured to the support structure through a portion 612 of thepolymeric strip extending from such second end to the support structure.In operation, the portion 612 of the polymeric strip disposed betweenthe second end of each connection section and the support structurebreaks when the connection section of the lead is forced downwardly intoengagement with the electrical contact of the chip. In other respects,this structure operates in substantially the same way as that describedabove with reference to FIGS. 15 and 16.

The component illustrated in FIG. 18 has connection sections 756 whichare cantilevered. That is, these connection sections project beyond edge741 of support structure 730, but the second ends 762 of such leads,remote from the edge 741 are not connected to the support structure.Stated another way, the projecting connection sections 756 of the leadsare attached to the support structure only at their respective firstends 758. Accordingly, this structure does not provide the enhancedalignment action achieved with the other embodiments in which the secondend of the lead is connected to the support structure. However, becauseeach lead incorporates a polymeric strip 710 overlying and bonded to itsmetallic structure, these leads will have the reinforcement discussedabove with reference to FIGS. 15, 16 and 17. That is, when the leads areflexed downwardly, the polymeric strips will reinforce the projectingportions of the metallic structure against stress concentration,particularly at and adjacent the edge of the support structure.

The component illustrated in FIG. 19 has the metallic structure of itsleads 852, and its terminals 848, disposed on top of the polymeric toplayer 832. Strips 810 formed integrally with the polymeric top layer 832extend outwardly beyond edge 841 beneath the metallic structure of eachlead. Thus, the metallic structure of each lead is reinforced at thejuncture of connection section 856 and first end securement section 866,i.e., at and adjacent the point where the lead crosses the edge 841 ofthe support structure. Each polymeric strip 810, however, terminatesshort of the second end 862 of the connection section, so that a portionof the connection section 856 adjacent the second end 862 has anexposed, downwardly facing metallic surface for engagement with thecontact (not shown) of the chip. When the component of FIG. 19 isengaged with a chip, the connection section 856 of each lead is flexeddownwardly, breaking the frangible section 872 as discussed above. Hereagain, the polymeric reinforcing strip 810, closely overlying and bondedto the metallic structure of the lead, reinforces the lead againststress concentration, particularly at adjacent edge 841.

As will be readily appreciated, the features of the various embodimentsdiscussed above can be combined with one another. For example, thevarious connection components illustrates and discussed above asincluding both a top layer and a bottom layer in their respectivesupport structures can be formed without the bottom layer and used witha separate bottom layer similar to that discussed above with referenceto FIGS. 10 and 11. Alternatively, the bottom layer can be omittedentirely.

A process for making a connection component incorporating a lead with afrangible section is illustrated in FIGS. 20A-20G. The process startswith a sheet of polyimide or other thin, flexible dielectric material902. The sheet has holes 904 formed therein at locations where terminalsare desired. A thin layer of copper is deposited non-selectively overthe entire sheet, so as to form thin copper layers 906 and 908 on thetop surface and bottom surface, respectively, of sheet 902, and also todeposit a thin layer of copper 910 extending through the holes 904.Using a conventional photoresist process, a heavy, structural layer ofcopper, typically about 0.01 mm to about 0.1 mm thick is appliedselectively in holes 904 to form plated “barrel” structures 912 and isalso applied selectively on bottom layer 908 so as to form elongatedstrips 914 on the bottom surface of the sheet where conductors aredesired. Strips 914 merge with the copper layer 908 on the bottomsurface of the sheet. A pattern of photoresist 907 is used inselectively forming strips 914. Resist pattern 907 incorporates a massof resist 916 covering bottom copper layer 908 at a preselected pointalong the length of each strip 914. This resist mast 916 thus forms aninterruption in each strip 914. However, the elements of strip 914 onopposite sides of this mass are interconnected by a thin web 917 ofcopper originally part of copper layer 908. A layer of a supplementalmetal, in this case gold, is then selectively applied on the same areasas the copper, i.e., on the strips 914 and on barrels 912. In the nextstage of the process (FIG. 20B), the photoresist material 907 used inthe steps discussed above is removed, and a new photoresist material 920is non-selectively applied over the entire bottom surface. The topsurface of the sheet is then subjected to an etching process of limitedduration. The limited etching process removes the thin copper layer 906from top surface of the sheet, but it does not substantially attack theplated barrels 910.

In the next stage of the process, a further photoresist 922 is appliedto the top surface of the sheet. That photoresist has holes aligned withplated barrels 912, so that the plated barrels are left uncovered.Moreover, top photoresist 922 has spaces 924. Those spaces are alignedwith the interruptions in strips 914, and hence with the thin webs 917left in each strip. As seen in FIG. 20C, each such interruption and thinweb 917 is disposed adjacent one side of space 924. In the next stage ofthe process (FIG. 20D), a mass of copper is deposited at the top of eachplated barrel 912 so as to form a terminal 926. A layer of nickel (notshown) is also deposited over this copper mass.

After the terminals 926 have been formed, the assembly is subjected to apolyimide etching step (FIG. 20E). Those areas of the polyimideunderlying spaces 924 in the top resist 922 are removed by the etchantso as to form gaps 528 in polyimide layer 906. The gaps are aligned withthe interruptions in strips 914, and hence aligned with the thin webs917 bridging these interruptions, each such interruption and thin webbeing disposed adjacent one side of the gap. The polyimide etchingprocess may be performed using well-known techniques as, for example,laser etching or plasma etching.

After the polyimide has been etched, and while the bottom resist layeris still in place, a thin layer 930 of a supplemental material, in thiscase gold, is applied on strips 914 by plating. Gold layer 930 alsocovers the thin copper webs 917 extending across the interruption ineach strip 914 (FIG. 20F). Thus, gold layer 930 extends across each suchinterruption. Following deposition of layer 930, the bottom photoresist920 is stripped from the assemblage, and the bottom surface of theassemblage is subjected to a sub-etching process similar to thatdiscussed above. This sub-etching process is sufficient to remove allexposed portions of layer 908, but does not appreciably attack thegold-covered copper in strips 914. Because thin webs 917 are uncoveredat this point, they are removed in the sub-etching process (FIG. 20G).This leaves a structure as discussed above with reference to FIG. 3.Thus, the copper structural material of the strips 914 is covered by thegold supplemental materials on its top and bottom surfaces, and thecopper structural material is interrupted at a frangible sectionadjacent one edge of gap 928. Thus, portions of the copper lead onopposite sides of each such gap are connected to one another only by athin web of the gold supplemental material 930.

In the foregoing process, the lead is supported at both ends whileforming the frangible section and also while forming the dielectricsupporting material to its final configuration, i.e., while forming thegap in the dielectric support layer. In this case, the lead is supportedby the dielectric material itself, and the dielectric material is etchedaway to form the gap. However, a reverse process could also be employed,wherein the lead is supported at both ends by a photoresist or othertemporary layer and the dielectric material is selectively deposited soas to form a structure having a gap aligned with the frangible sectionof the lead. Conversely, the gap in the dielectric support layer can beformed first, and the lead can be deposited and etched to form thefrangible section. The materials used in the process can be varied, andmay include the different structural and supplemental materialsdiscussed above.

A process for making a connection component having a permanently securedfirst end securement section and a detachable second end securementsection is schematically illustrated in FIGS. 21A through 21H. Theprocess begins with a laminate including a substantially continuousdielectric support layer 1002 of polyimide or another suitable polymerand a thin layer 1004 of copper or other suitable conductive material onthe bottom surface on the dielectric support layer 1002. Utilizingconventional masking and selective electroplating techniques, strips ofgold or other suitable lead material 1006 are deposited on copper layer1004 in a side-by-side array. Only one such strip is visible in FIG.21B. After deposition of the gold strips 1006 and removal of anytemporary masking material used for that process, a layer of photoresist1008 is deposited on the gold strips and copper layer.

Openings 1010 (FIG. 21C) are etched through polyimide layer 1002 and,desirably, through copper layer 1004 as well. One such opening 1010 isprovided for each gold strip 1006, so that the top surface of each goldstrip is exposed in one such opening. A bump contact is formed withineach such opening 1010. As seen in FIG. 21D, each such bump contactincludes a mask 1012 of a base metal such as copper in electricalcontact with the associated gold strip 1006 and an overlayer 1014 of asolderable, chemically resistant metal such as nickel, gold or alloysthereof. Following deposition of the bump contacts, photoresist layer1008 is removed and the thin copper layer 1004 is also removed from theunderside of polyimide layer 1002 except in the areas covered by goldstrips 1006. This electrically isolates the individual gold strips 1006from one another, leaving the assembly in the condition illustrated inFIG. 21E.

Next, a substantially continuous layer of a relatively soft, compliantsolder mask material 1016 is applied on the bottom surface of polyimidelayer 1002 and on strips 1006 (FIG. 21F). Using etching processes asdiscussed above in connection with FIGS. 20A through 20G, a gap 1018 isetched into polyimide support layer 1002 whereas a further gap 1020 isformed in underlayer 1016. As illustrated in FIG. 21E, the gap 1018 insupport layer 1002 overlies a connection section or part 1026 of strip1006 relatively close to one end of the strip. Thus, a relatively longfirst end securement section 1022 of each strip 1006 remains attached tosupport layer 1002 on one side of gap 1018 whereas a relatively shortsecond end securement section 1024 remains attached to layer 1002 on theother side of gap 1018. As used with reference to portions of strip1006, the terms “long” and “short” refer to the lengths of theseportions in the direction of elongation of strip 1006, i.e., in thedirections from left to right and right to left in FIG. 21G. Merely byway of example, the second end securement section 1024 may be about0.025 mm to about 0.075 mm long, as measured from the adjacent edge 1028of gap 1018 to the end 1030 of strip 1006 at the second end securementsection. The first end securement section 1022 desirably is longer thanthe second end securement section. Thus, the first end securementsection 1022 may be at least about 1.25 mm long, as measured from theadjacent edge 1032 of gap 1018 to the end 1034 of strip 1006 boundingthe first end securement section 1022. The bump contact 1012 1014 isdisposed on the first end securement section 1022.

The gap 1020 in underlayer 1016 is slightly larger than the gap 1018 indielectric support layer 1002. Gap 1020 is partially aligned with gap1018 so that gap 1020 encompasses the connection section 1026 of thestrip and also encompasses the second end securement section 1024. Thus,the first end securement section 1022 remains engaged between underlayer1016 and support layer 1002 whereas the second end securement section1024 is exposed through gap 1000. In the next stage of the process (FIG.21h) the residual portion of copper layer 1004 remaining on the strip1006 is removed in the connection portion 1026 of the strip, leaving thelead with first end securement section 1022, connection section 1026 andsecond end securement section 1024. Because second end securementsection 1024 is connected to the dielectric support layer 1002 over onlya very short length, and hence a very small area, and because the secondend securement section 1024 is unsupported by the underlayer 1016, thesecond end securement section can be detached readily from the supportlayer when the connection section 1026 is engaged by a bonding tool.Conversely, the first end securement section is securely bonded to thedielectric support layer 1002 over a substantial length, and issupported by the underlayer 1016, so that the first end securementsection is substantially permanently connected to the dielectric supportlayer.

In all of the embodiments illustrated above, the connection sections ofthe leads are bonded to contacts on the chip. However, similarcomponents and methods can be used for bonding to a substrate or toanother component of a semiconductor chip assemblage. Such a variant isschematically shown in FIG. 22. The connection component 1200 has adielectric supporting structure 1202 similar to those discussed above.The supporting structure 1202 defines gaps 1204. Numerous leads areprovided, which only a few are shown in FIG. 22. Each lead has aconnection section 1206 which, prior to assembly, extends across a gap1204. Each lead also has a terminal 1208 remote from gap 1204. In theassembly procedure, the terminals 1208 are connected to terminals on asemiconductor chip 1210 whereas the connection sections 1206 of theleads are connected to contacts 1212 on a chip mount, hybrid circuitpanel or other supporting substrate 1214. The configurations of theconnection sections 1206 may be similar to any of those discussed above.Also, the bonding procedures used for bonding the connection sections tothe contacts of the substrate may be essentially the same as thosediscussed above with reference to bonding to a chip. According to yet afurther variant (not shown) the terminals 1208 may be replaced by afurther set of connection sections and further gaps in the supportingstructure. In this arrangement, each individual lead has two separateconnection sections extending across two separate gaps in the supportingstructure. The leads and gaps are configured so that when the connectioncomponent is disposed on an assemblage of a chip and substrate, one setof connection sections is positioned atop contacts on the chip, whereasanother set of connection sections, and the associated gaps, arepositioned atop contacts on the substrate. In this arrangement, thebonding procedures discussed above may be used both for bonding theleads to the chip and for bonding the leads to the substrate.

As these and other variations, combinations and modifications of thefeatures discussed above can be employed without departing from thepresent invention, the foregoing description of the preferredembodiments should be taken by way of illustration rather than by way oflimitation of the present invention as defined by the claims.

What is claimed is:
 1. A semiconductor chip mounting component forassembly with a semiconductor chip, said component comprising: (a) asupport structure having top and bottom surfaces and an edge; (b) aplurality of electrically conductive leads, each of said leads having afirst end securement section secured to said support structure andhaving a connection section integral with said first end securementsection projecting beyond said edge of said support structure; and (c) aplurality of flexible, polymeric reinforcements, each of saidreinforcements being in contact with and extending along said connectionsection of one of said leads, each of said polymeric reinforcementsbeing separate from said polymeric reinforcements in contact with othersof said leads, each of said polymeric reinforcements extending beyondsaid edge of said support structure, wherein each said connectionsection is flexible and may be individually displaced withoutdisplacement of connection sections of adjacent ones of said leads, saidcomponent not having a chip connected to said leads.
 2. A component asclaimed in claim 1 wherein said polymeric reinforcements are in contactwith said leads at said edge, whereby said polymeric reinforcements willinhibit stress concentration in said leads at said edge.
 3. A componentas claimed in claim 2 wherein the connection section and first endsecurement section of each of said leads includes a unitary metallicstrip, said polymeric reinforcements of said leads including polymericstrips extending codirectionally with said metallic strips.
 4. Acomponent as claimed in claim 3 wherein said support structure includesa polymeric layer, said polymeric strips being formed integrally withsaid polymeric layer.
 5. A component as claimed in claim 4 wherein saidmetallic strips have generally planar upper surfaces, and wherein saidpolymeric strips and polymeric layer are disposed above said metallicstrips in contact with said upper surfaces.
 6. A component as claimed inclaim 5 wherein said metallic strips are less than about 0.25 mm thick.7. A component as claimed in claim 1, wherein the connection sections ofat least some of said leads are substantially parallel to one another.8. A component as claimed in claim 1, wherein at least some of saidleads are adjacent one another.
 9. A component as claimed in claim 1,wherein the connection sections of at least some of said leads aredisposed in a substantially side-by-side array.
 10. A semiconductor chipmounting component for assembly with a semiconductor chip, saidcomponent comprising: (a) a support structure having top and bottomsurfaces and an edge; (b) a plurality of electrically conductive leads,each of said leads having a first end securement section secured to saidsupport structure and having a connection section integral with saidfirst end securement section projecting beyond said edge of said supportstructure, said connection section and said first end securement sectionof each of said leads including a unitary metallic strip, each saidconnection section being flexible relative to said support structure toengage a contact; and (c) a plurality of flexible, polymericreinforcements, each of said reinforcements being in contact with andextending along said connection section of one of said leads, each ofsaid polymeric reinforcements extending beyond said edge of said supportstructure and being separate from said polymeric reinforcements incontact with others of said leads, whereby said polymeric reinforcementswill inhibit stress concentrations in said leads at said edge, each saidpolymeric reinforcement including a polymeric strip extendingco-directionally with said unitary metallic strip, said component nothaving a chip connected to said leads.
 11. A component as claimed inclaim 10, wherein said support structure includes a polymeric layer, andsaid polymeric strips are formed integrally with said polymeric layer.12. A component as claimed in claim 11, wherein said metallic stripshave generally planar upper surfaces, and wherein said polymeric stripsand polymeric layer are disposed above said metallic strips in contactwith said upper surfaces.
 13. A component as claimed in claim 12,wherein said metallic strips are less than about 0.25 mm thick.
 14. Acomponent as claimed in claim 10, wherein the connection sections of atleast some of said leads are substantially parallel to one another. 15.A component as claimed in claim 10, wherein at least some of said leadsare adjacent one another.
 16. A component as claimed in claim 10,wherein the connection sections of at least some of said leads aredisposed in a substantially side-by-side array.
 17. A component asclaimed in claim 10, wherein said polymeric reinforcements are integralwith said support structure.